1. Field of the Invention
The present invention relates to overhead projectors, and particularly to portable overhead projectors of the transmissive type.
2. Description of the Prior Art
In general, an overhead projector comprises a housing containing a light source and a stage means for supporting a Fresnel lens and on which may be disposed a transparency bearing an image to be projected. Light from the source is directed through the stage and the transparency to a projection head which is supported on a mast above the housing, the projection head including a reflecting mirror and a projection lens for directing and focusing an image from the transparency to a remote viewing surface.
The projection head and mast may be foldable to a stowage configuration when not in use. Furthermore, it is known to provide overhead projectors of this type in a portable form, so that all the parts may be disposed in the housing for transportation and storage.
However, in most prior art portable overhead projectors, it is necessary to remove and/or disassemble parts of the device in order to move it to its storage or transportation configuration. It is known to provide a portable overhead projector which does not require disassembly, such a projector being disclosed in U.S. Pat. No. 3,653,754. However, that projector has a large and bulky housing and requires a rather complex series of folding steps in order to move the parts between their use and storage configurations.